They cleaved to a radical vegan diet, a Manichean image of the nature of good and evil, pacifism, and rejection of the doctrine that Jesus of Nazareth had a corporeal and incorporeal nature. They held that the Catholic Church was evil, that the only true Christian faithful were the ”parfaits” (or ”perfecti,” or ”perfect ones”), known by the poverty and asceticism of their lives. Worldly wealth of the monastery, cathedral, or feudatory was a sure sign of sin, corruption, and faithlessness. This change was hotly condemned as heretical by the Church, which was eagerly supported by outraged northern French nobility. The Cathar revolt against the corrupt rich of clergy and nobility was the gravest challenge to the authority of the Church prior to theHussite Wars and the Protestant Reformation.

The Church responded to the recruiting success of the sect’s ascetic preachers, including conversion of some southern nobles, by sending Bernard of Clairvaux and his Cistercian brethren, followed later by St. Dominic and his fanatic friars, to counterpreach in Cathar areas. The contest turned violent from 1208 when a papal legate was murdered. Pope Innocent III (r.1198-1216) retaliated by proclaiming a crusade against the Cathar ”heretics.” Catholics lined up behind a regional warlord, Simon de Montfort, while Cathars looked to their noble converts and hired thousands of routiers. They also accepted informal alliance with Aragon, which had designs on Languedoc.

The northern nobility savagely repressed the Cathars, burning and wreaking much of Languedoc in a brutal guerre mortelle. They massacred by sword and burned Cathars at the stake, and killed routiers with merciless cruelty. In fact, so many routiers died that France enjoyed an unusual internal peace of several decades once the Cathar wars ended. Among the horrors of a notoriously awful war, Simon de Montfort had the population of the town of Bram blinded, except for an old man he left to guide them. In an unconnected act of justice, he was killed in 1218 by a stone trebuchet ball (”pomme”) reportedly fired toward him by women from inside fortified Toulouse, which he was besieging.

As was usual in medieval warfare, the Cathar wars were a matter of sieges and savage chevauche´es rather than set-piece battles. Only one large battle took place, at Muret (September 12, 1213), where de Montfort defeated a Cathar-Catalan army. In addition to the religious divide the war spoke to regional rivalry: Languedoc nobles who protected the Cathars were besieged in their great castles by armies of Catholic knights from the north. The Catholics brought with them the new counterweight trebuchet, with which they battered down thin-walled southern castles. Capetian monarchs also used the war to expand royal reach into Languedoc: Louis VIII personally led an expedition south in 1226. After most fighting ended in 1229 a Dominican Inquisition set out to ferret out lingering ”heresy.” Over several decades all Cathars were hunted down and their belief eradicated. However, powerful regional resentments of northern and Catholic power lingered to play some role in the French Civil Wars, and even after.